First off I'm not in beta, my thoughts are based on what I have read about it.
At the moment stamina stacking is the only option for tanking, for a while I tried to go against that wisdom and I did try building up avoidance, but after discussion with my healers I changed and tested it... anyway, it's pretty much accepted that stacking stamina is the way to go.
My concern is that it will be even more so in Cataclysm than it is currently. I have a number of reasons that I think this will be so, but the primary reason is Vengeance. Simply put, for gearing up a tank there are three broad areas to look at: threat, damage reduction, and total health. At present stacking stamina only affects total health (or if you prefer effective health), when vengeance is implemented stacking stamina will also increase your threat as well. In my view significantly increasing its comparative value, which already dominates. I know this will be most noticeable at end game which isn't yet open for testing, but I am curious to hear what other tanks think about this.
I personally think juggling stats to get a balance is more fun than stacking one thing and ignoring everything else, and I think this is a negative concentration on a single stat.
Whatever you think, thank you for reading.